#!/usr/bin/env python


__license__ = 'GPL v3'
__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'

import errno
import os
import re
import shutil
import sys
from collections import OrderedDict, namedtuple
from contextlib import suppress
from locale import localeconv
from threading import Lock

from calibre import as_unicode, prints
from calibre.constants import cache_dir, get_windows_number_formats, iswindows, preferred_encoding
from calibre.utils.icu import lower as icu_lower
from calibre.utils.localization import canonicalize_lang, ngettext


def force_to_bool(val):
    if isinstance(val, (bytes, str)):
        if isinstance(val, bytes):
            val = val.decode(preferred_encoding, 'replace')
        try:
            val = icu_lower(val)
            if not val:
                val = None
            elif val in [_('yes'), _('checked'), 'true', 'yes']:
                val = True
            elif val in [_('no'), _('unchecked'), 'false', 'no']:
                val = False
            else:
                val = bool(int(val))
        except Exception:
            val = None
    return val


_fuzzy_title_patterns = None


def fuzzy_title_patterns():
    global _fuzzy_title_patterns
    if _fuzzy_title_patterns is None:
        from calibre.ebooks.metadata import get_title_sort_pat
        _fuzzy_title_patterns = tuple((re.compile(pat, re.IGNORECASE) if
            isinstance(pat, (str, bytes)) else pat, repl) for pat, repl in
                [
                    (r'[\[\](){}<>\'";,:#]', ''),
                    (get_title_sort_pat(), ''),
                    (r'[-._]', ' '),
                    (r'\s+', ' ')
                ]
        )
    return _fuzzy_title_patterns


def fuzzy_title(title):
    title = icu_lower(title.strip())
    for pat, repl in fuzzy_title_patterns():
        title = pat.sub(repl, title)
    return title


def find_identical_books(mi, data):
    author_map, aid_map, title_map, lang_map = data
    found_books = None
    for a in mi.authors:
        author_ids = author_map.get(icu_lower(str(a)))
        if author_ids is None:
            return set()
        books_by_author = {book_id for aid in author_ids for book_id in aid_map.get(aid, ())}
        if found_books is None:
            found_books = books_by_author
        else:
            found_books &= books_by_author
        if not found_books:
            return set()

    ans = set()
    titleq = fuzzy_title(mi.title)
    for book_id in found_books:
        title = title_map.get(book_id, '')
        if fuzzy_title(title) == titleq:
            ans.add(book_id)

    langq = tuple(filter(lambda x: x and x != 'und', map(canonicalize_lang, mi.languages or ())))
    if not langq:
        return ans

    def lang_matches(book_id):
        book_langq = lang_map.get(book_id)
        return not book_langq or langq == book_langq

    return {book_id for book_id in ans if lang_matches(book_id)}


Entry = namedtuple('Entry', 'path size timestamp thumbnail_size')


class CacheError(Exception):
    pass


class ThumbnailCache:
    ' This is a persistent disk cache to speed up loading and resizing of covers '

    def __init__(self,
                 max_size=1024,  # The maximum disk space in MB
                 name='thumbnail-cache',  # The name of this cache (should be unique in location)
                 thumbnail_size=(100, 100),   # The size of the thumbnails, can be changed
                 location=None,   # The location for this cache, if None cache_dir() is used
                 test_mode=False,  # Used for testing
                 min_disk_cache=0,  # If the size is set less than or equal to this value, the cache is disabled.
                 version=0  # Increase this if the cache content format might have changed.
                 ):
        self.version = version
        self.location = os.path.join(location or cache_dir(), name)
        if max_size <= min_disk_cache:
            max_size = 0
        self.max_size = int(max_size * (1024**2))
        self.group_id = 'group'
        self.thumbnail_size = thumbnail_size
        self.size_changed = False
        self.lock = Lock()
        self.min_disk_cache = min_disk_cache
        if test_mode:
            self.log = self.fail_on_error

    def log(self, *args, **kwargs):
        kwargs['file'] = sys.stderr
        prints(*args, **kwargs)

    def fail_on_error(self, *args, **kwargs):
        msg = ' '.join(args)
        raise CacheError(msg)

    def _do_delete(self, path):
        try:
            os.remove(path)
        except OSError as err:
            self.log('Failed to delete cached thumbnail file:', as_unicode(err))

    def _load_index(self):
        '''
        Load the index, automatically removing incorrectly sized thumbnails and
        pruning to fit max_size
        '''

        # Remove the cache if it isn't the current version
        version_path = os.path.join(self.location, 'version')
        current_version = 0
        with suppress(Exception), open(version_path) as f:
            current_version = int(f.read())
        if current_version != self.version:
            # The version number changed. Delete the cover cache. Can't delete
            # it if it isn't there (first time). Note that this will not work
            # well if the same cover cache name is used with different versions.
            if os.path.exists(self.location):
                shutil.rmtree(self.location)

        try:
            os.makedirs(self.location)
            with open(version_path, 'w') as f:
                f.write(str(self.version))
        except OSError as err:
            if err.errno != errno.EEXIST:
                self.log('Failed to make thumbnail cache dir:', as_unicode(err))
        self.total_size = 0
        self.items = OrderedDict()
        order = self._read_order()

        def listdir(*args):
            try:
                return os.listdir(os.path.join(*args))
            except OSError:
                return ()  # not a directory or no permission or whatever
        entries = ('/'.join((parent, subdir, entry))
                   for parent in listdir(self.location)
                   for subdir in listdir(self.location, parent)
                   for entry in listdir(self.location, parent, subdir))

        invalidate = set()
        try:
            with open(os.path.join(self.location, 'invalidate'), 'rb') as f:
                raw = f.read().decode('utf-8')
        except OSError as err:
            if getattr(err, 'errno', None) != errno.ENOENT:
                self.log('Failed to read thumbnail invalidate data:', as_unicode(err))
        else:
            try:
                os.remove(os.path.join(self.location, 'invalidate'))
            except OSError as err:
                self.log('Failed to remove thumbnail invalidate data:', as_unicode(err))
            else:
                def record(line):
                    try:
                        uuid, book_id = line.partition(' ')[0::2]
                        book_id = int(book_id)
                        return uuid, book_id
                    except Exception:
                        return None
                invalidate = {record(x) for x in raw.splitlines()}
        items = []
        try:
            for entry in entries:
                try:
                    uuid, name = entry.split('/')[0::2]
                    book_id, timestamp, size, thumbnail_size = name.split('-')
                    book_id, timestamp, size = int(book_id), float(timestamp), int(size)
                    thumbnail_size = tuple(map(int, thumbnail_size.partition('x')[0::2]))
                except (ValueError, TypeError, IndexError, KeyError, AttributeError):
                    continue
                key = (uuid, book_id)
                path = os.path.join(self.location, entry)
                if self.thumbnail_size == thumbnail_size and key not in invalidate:
                    items.append((key, Entry(path, size, timestamp, thumbnail_size)))
                    self.total_size += size
                else:
                    self._do_delete(path)
        except OSError as err:
            self.log('Failed to read thumbnail cache dir:', as_unicode(err))

        self.items = OrderedDict(sorted(items, key=lambda x: order.get(x[0], 0)))
        self._apply_size()

    def _invalidate_sizes(self):
        if self.size_changed:
            size = self.thumbnail_size
            remove = tuple(key for key, entry in self.items.items() if size != entry.thumbnail_size)
            for key in remove:
                self._remove(key)
            self.size_changed = False

    def _remove(self, key):
        entry = self.items.pop(key, None)
        if entry is not None:
            self._do_delete(entry.path)
            self.total_size -= entry.size

    def _apply_size(self):
        while self.total_size > self.max_size and self.items:
            entry = self.items.popitem(last=False)[1]
            self._do_delete(entry.path)
            self.total_size -= entry.size

    def _write_order(self):
        if hasattr(self, 'items'):
            try:
                data = '\n'.join(group_id + ' ' + str(book_id) for (group_id, book_id) in self.items)
                with open(os.path.join(self.location, 'order'), 'wb') as f:
                    f.write(data.encode('utf-8'))
            except OSError as err:
                self.log('Failed to save thumbnail cache order:', as_unicode(err))

    def _read_order(self):
        order = {}
        try:
            with open(os.path.join(self.location, 'order'), 'rb') as f:
                for line in f.read().decode('utf-8').splitlines():
                    parts = line.split(' ', 1)
                    if len(parts) == 2:
                        order[(parts[0], int(parts[1]))] = len(order)
        except Exception as err:
            if getattr(err, 'errno', None) != errno.ENOENT:
                self.log('Failed to load thumbnail cache order:', as_unicode(err))
        return order

    def shutdown(self):
        with self.lock:
            self._write_order()

    def set_group_id(self, group_id):
        with self.lock:
            self.group_id = group_id

    def set_thumbnail_size(self, width, height):
        new_size = (width, height)
        with self.lock:
            if new_size != self.thumbnail_size:
                self.thumbnail_size = new_size
                self.size_changed = True
                return True
        return False

    def insert(self, book_id, timestamp, data):
        if self.max_size < len(data):
            return
        with self.lock:
            if not hasattr(self, 'total_size'):
                self._load_index()
            self._invalidate_sizes()
            ts = (f'{timestamp:.2f}').replace('.00', '')
            path = f'{self.group_id}{os.sep}{book_id % 100}{os.sep}{book_id}-{ts}-{len(data)}-{self.thumbnail_size[0]}x{self.thumbnail_size[1]}'
            path = os.path.join(self.location, path)
            key = (self.group_id, book_id)
            e = self.items.pop(key, None)
            self.total_size -= getattr(e, 'size', 0)
            try:
                with open(path, 'wb') as f:
                    f.write(data)
            except OSError as err:
                d = os.path.dirname(path)
                if not os.path.exists(d):
                    try:
                        os.makedirs(d)
                        with open(path, 'wb') as f:
                            f.write(data)
                    except OSError as err:
                        self.log('Failed to write cached thumbnail:', path, as_unicode(err))
                        return self._apply_size()
                else:
                    self.log('Failed to write cached thumbnail:', path, as_unicode(err))
                    return self._apply_size()
            self.items[key] = Entry(path, len(data), timestamp, self.thumbnail_size)
            self.total_size += len(data)
            self._apply_size()

    def __len__(self):
        with self.lock:
            try:
                return len(self.items)
            except AttributeError:
                self._load_index()
                return len(self.items)

    def __contains__(self, book_id):
        with self.lock:
            try:
                return (self.group_id, book_id) in self.items
            except AttributeError:
                self._load_index()
                return (self.group_id, book_id) in self.items

    def __getitem__(self, book_id):
        with self.lock:
            if not hasattr(self, 'total_size'):
                self._load_index()
            self._invalidate_sizes()
            key = (self.group_id, book_id)
            entry = self.items.pop(key, None)
            if entry is None:
                return None, None
            if entry.thumbnail_size != self.thumbnail_size:
                try:
                    os.remove(entry.path)
                except OSError as err:
                    if getattr(err, 'errno', None) != errno.ENOENT:
                        self.log('Failed to remove cached thumbnail:', entry.path, as_unicode(err))
                self.total_size -= entry.size
                return None, None
            self.items[key] = entry
            try:
                with open(entry.path, 'rb') as f:
                    data = f.read()
            except OSError as err:
                self.log('Failed to read cached thumbnail:', entry.path, as_unicode(err))
                return None, None
            return data, entry.timestamp

    def invalidate(self, book_ids):
        with self.lock:
            if hasattr(self, 'total_size'):
                for book_id in book_ids:
                    self._remove((self.group_id, book_id))
            elif os.path.exists(self.location):
                try:
                    raw = '\n'.join(f'{self.group_id} {book_id}' for book_id in book_ids)
                    with open(os.path.join(self.location, 'invalidate'), 'ab') as f:
                        f.write(raw.encode('ascii'))
                except OSError as err:
                    self.log('Failed to write invalidate thumbnail record:', as_unicode(err))

    @property
    def current_size(self):
        with self.lock:
            if not hasattr(self, 'total_size'):
                self._load_index()
            return self.total_size

    def empty(self):
        with self.lock:
            try:
                os.remove(os.path.join(self.location, 'order'))
            except OSError:
                pass
            if not hasattr(self, 'total_size'):
                self._load_index()
            for entry in self.items.values():
                self._do_delete(entry.path)
            self.total_size = 0
            self.items = OrderedDict()

    def __hash__(self):
        return id(self)

    def set_size(self, size_in_mb):
        if size_in_mb <= self.min_disk_cache:
            size_in_mb = 0
        size_in_mb = max(0, size_in_mb)
        with self.lock:
            self.max_size = int(size_in_mb * (1024**2))
            if hasattr(self, 'total_size'):
                self._apply_size()


number_separators = None


def atof(string):
    # Python 2.x does not handle unicode number separators correctly, so we
    # have to implement our own
    global number_separators
    if number_separators is None:
        if iswindows:
            number_separators = get_windows_number_formats()
        else:
            lc = localeconv()
            t, d = lc['thousands_sep'], lc['decimal_point']
            if isinstance(t, bytes):
                t = t.decode('utf-8', 'ignore') or ','
            if isinstance(d, bytes):
                d = d.decode('utf-8', 'ignore') or '.'
            number_separators = t, d
    return float(string.replace(number_separators[1], '.').replace(number_separators[0], ''))


def type_safe_sort_key_function(keyfunc=None):
    if keyfunc is None:
        def keyfunc(x):
            return x
    sentinel = object()
    first_value = sentinel

    def key(x):
        nonlocal first_value
        ans = keyfunc(x)
        if first_value is sentinel:
            first_value = ans
        else:
            try:
                ans < first_value
                first_value < ans
            except TypeError:
                ans = first_value
        return ans

    return key


def human_readable_interval(secs):
    secs = int(secs)
    days = secs // 86400
    hours = secs // 3600 % 24
    minutes = secs // 60 % 60
    seconds = secs % 60
    parts = []
    if days > 0:
        parts.append(ngettext('1 day', '{} days', days).format(days))
        if hours > 0:
            parts.append(ngettext('1 hour', '{} hours', hours).format(hours))
    elif hours > 0:
        parts.append(ngettext('1 hour', '{} hours', hours).format(hours))
        if minutes > 0:
            parts.append(ngettext('1 minute', '{} minutes', minutes).format(minutes))
    elif minutes > 0:
        parts.append(ngettext('1 minute', '{} minutes', minutes).format(minutes))
        if secs > 0:
            parts.append(ngettext('1 second', '{} seconds', seconds).format(seconds))
    elif secs > 0:
        parts.append(ngettext('1 second', '{} seconds', seconds).format(seconds))
    return ' '.join(parts)


class IndexingProgress:

    def __init__(self):
        self.reset()

    def __repr__(self):
        return f'IndexingProgress(left={self.left}, total={self.total}, rate={self.indexing_rate})'

    def reset(self):
        self.left = self.total = -1
        self.indexing_rate = None

    def update(self, left, total, indexing_rate):
        changed = (left, total, indexing_rate) != (self.left, self.total, self.indexing_rate)
        self.indexing_rate = indexing_rate
        self.left, self.total = left, total
        return changed

    @property
    def complete(self):
        return not self.left or not self.total

    @property
    def almost_complete(self):
        return self.complete or (self.left / self.total) < 0.1

    @property
    def time_left(self):
        if self.left < 0:
            return _('calculating time left')
        if self.left < 2:
            return _('almost done')
        if self.indexing_rate is None:
            return _('calculating time left')
        try:
            seconds_left = self.left / self.indexing_rate
            if seconds_left < 2:
                return _('almost done')
            return _('~{} left').format(human_readable_interval(seconds_left))
        except Exception:
            return _('calculating time left')
